The worsening climate situation reveals the inability of the market system and of economic policy to deal with what conventional economics calls ”externalities”. We are faced with hard material constraints that any viable alternative to capitalism must be able to deal with. For example, we must produce a diverse basket of basic consumption goods, a certain number of hospital beds, and so on, while maintaining 10 gigaton per year net carbon dioxide sequestration. This challenge bears many similarities to problems considered in the study of cybernetics. One qualitative change from the socialist calculation debate of the 1920’s is the invention of the digital computer and the internet. The rising computer-literacy in the population enables democratic computerized planning that can coordinate individual workplaces on a large scale. Our aim with this talk is twofold: on the one hand, to spark renewed interest around the potentials and challenges of cybernetic planning, and on the other hand, initiate development of and experimentation with such methods in the real world. The talk begins with a brief history of planning, from Marx and Engels to Otto Neurath and Gosplan, and to modern thinkers like Stafford Beer and Paul Cockshott. We then go on to discuss how computerized macroeconomic coordination can be carried out that takes into account explicit material constraints. Such a system can continuously adjust recommended reallocations of productive resources, adapting to changes in the real world as fast as information can be put into the system and as fast as people can react to the suggestions provided by the system. We identify maintaining viability as a key necessity of any post-capitalist economic system. By contrast, the consequences of runaway climate change is laying bare the inability of capitalist market economies to maintain viability. To turn a neoliberal slogan, there is no alternative to planning!